1. Field of the Invention
The present invention relates to a laser printer apparatus in which a so-called semiconductor laser array comprising a plurality of light-emitting devices arranged in a row is used as a light source, light from the light source is guided onto a surface to be scanned, and a reproduced image is formed on this surface.
2. Description of the Prior Art
In recent years, laser printer apparatus have been employed in various kinds of office machines. Generally used as their light-scanning means are well-known polygon mirrors.
While the polygon mirrors are superior to galvanometer mirrors in terms of high-speed scanning or good shading, they may be problematic, due to fluctuations in surface accuracy or face-tilting amount among mirror faces, in fine curves of scanning lines, fluctuations in scanning pitches, and fluctuations in lengths of scanning lines.
Also, scanning apparatus using such a polygon mirror necessitate a sensor for attaining a timing for scanning in order to make starting points of respective scanning lines coincide with each other.
Further, in the scanning apparatus using such a polygon mirror, vibrations and noises are likely to occur due to the rotating action of their rotary driving section.
Thus, since various problems such as those mentioned above may occur when a polygon mirror is employed as light-scanning means, there has been a demand for developing a technique for scanning a laser beam without using a polygon mirror.
Also, together with such a technique, it becomes necessary to develop an imaging optical system suitable for this technique, which can favorably guide a luminous flux from a laser light source onto the surface to be scanned when such a technique is used.